EP2902201A2 - Device and method of manufacturing a structured surface on a printing substrate - Google Patents

Abstract

Apparatus for producing a structured surface on a printing substrate, comprising at least the following components: a coating unit (14) for applying a lacquer layer (18) to a printing material (11); a coater (15) downstream of the coating unit (14) for transferring a three-dimensional structure to the lacquer layer (18) applied to the substrate by means of the coating unit (14) before drying thereof; a drying device (16) downstream of the embossing unit (15) for drying the lacquer layer (18) applied by means of the coating unit (14) and structured by means of the embossing unit (15) to form the structured surface on the printing material (11).

Description

The invention relates to a device for producing a structured surface on a printing substrate. Furthermore, the invention relates to a method for producing a structured surface on a printing substrate. The invention further relates to a method for producing a stamping die.

For printing on printing substrates, sheet-fed printing presses and web-fed printing presses are well known in practice. In sheetfed presses, sheet-shaped substrates and web-fed substrates are printed. These printing presses may be conventional, printing-form-based printing machines or also printing-form-free, digital printing presses. For printing substrates with conventional sheet-fed presses or conventional web-fed printing presses, offset printing presses are preferably used.

From practice it is also already known to apply to the refinement of printed substrates on the same coatings. Such coatings can be transparent, transparent coatings as well as colored coatings. Thus, it is known from practice to apply coatings on a substrate, for example in coating plants, such coating plants can work, for example, by the offset printing process or flexographic printing process or gravure printing process or screen printing process. Furthermore, it is already known from the prior art to apply varnishes of variable layer thickness via inkjet printing processes, in this regard, the state of the art US Pat. No. 7,451,698 B2 directed.

For further differentiation of printed products, it is already known to form a three-dimensionally structured surface on printed products. These may be, for example, haptically perceptible surface structures, which may serve, for example, to provide a security function, such as an anti-counterfeiting function.

In order to form three-dimensionally structured and thus haptically perceptible surfaces on printed substrates, it is known from practice to machine the substrates with a mechanical embossing punch. In this case, a profile is embossed into the material structure of the printing substrate with a stamping mold under high pressure. The embossing is typically carried out from the back of the substrate to make the embossed image positively raised on the front of the substrate perceptible. In the embossing method known from practice, therefore, the material structure of the printing material is changed. A back of the substrate is no longer useful as a print image carrier. Furthermore, with such mechanical stamping dies, only on robust printing substrates can a structured surface be formed, namely on those printing substrates which are not damaged as a result of the mechanical stamping process. Films or thin paper materials can not be processed on the basis of their material structure with a mechanical stamping punch, because they are destroyed here.

There is therefore a need for a method and an apparatus for producing a structured surface on a printing material by means of which the above disadvantages can be avoided. In particular, films and thin paper materials should be able to be provided with a structured surface. Furthermore, the back of the substrate should not be rendered unusable as a print image carrier.

On this basis, the present invention has the object to provide a novel device for producing a structured surface on a substrate and a corresponding method.

This object is achieved by a device according to claim 1. The device according to the invention comprises at least the following components: a coating unit for applying a lacquer coating to a printing substrate; a coater downstream of the coating unit for transferring a three-dimensional structure into the lacquer layer applied to the printing material with the aid of the coating unit before drying thereof; a drying device arranged downstream of the embossing unit for drying the lacquer layer applied with the aid of the coating unit and structured with the aid of the embossing machine, forming the structured surface on the printing material. By means of the device according to the invention, the disadvantages known from practice in the formation of structured surfaces on a printing material can be avoided. With the device according to the invention even sensitive substrates such as films and thin paper materials can be provided with a structured surface. Another advantage of the invention is that the material structure of the printing material is not changed. Accordingly, both sides of a printing material can serve as a print image carrier or optionally be provided on both sides with a structured surface.

Preferably, however, the embossing machine does not transfer the three-dimensional structure exclusively into the lacquer layer applied with the aid of the lacquer coating before drying the same into the printing substrate which carries the lacquer layer. This ensures that the material structure of the substrate is not changed or even damaged during the formation of the structured surface.

According to an advantageous embodiment of the invention, the embossing machine has a stamping die carrying a stamping cylinder and cooperating with the stamping cylinder counter cylinder, wherein the substrate provided with paint layer is movable through an embossing gap formed between the embossing cylinder and the counter cylinder while transmitting the three-dimensional structure.

Such a design of the embossing mill is particularly advantageous. This high processing speeds can be realized in the production or training of the structured surface on the substrate, namely those speeds that are adapted to the printing speeds of known printing machines. As a result, the device is particularly suitable for integration into a printing machine designed as a sheet-fed printing press or as a web-fed printing press, in order to form the structured surfaces inline with the printing process at high speed on the printed substrates.

Preferably, the cylinder group of the embossing machine comprising the embossing cylinder and the counter-cylinder is driven in an eigenmotor manner via a direct drive. Then, when the cylinder group of the embossing machine, which includes the embossing cylinder and the counter-cylinder cooperating with the embossing cylinder, is driven by an engine, this cylinder group can be synchronized to the rest of the printing process. In this case, no sluggish or braking slip occurs at the cylinder group of the embossing mill, so that structured surfaces of high quality can be formed on the printing substrates.

The method according to the invention for producing a structured surface on a printing substrate is defined in claim 12. The method according to the invention for producing a stamping die for use in the method according to the invention and / or in the method according to the invention is defined in claims 15 and 16.

Fig. 3

eine schematisierte Vorrichtung zum Herstellen einer strukturierten Oberfläche auf einem bogenförmigen Bedruckstoff nach einer ersten Variante der Erfindung;

Fig. 4

eine schematisierte Vorrichtung zum Herstellen einer strukturierten Oberfläche auf einem bogenförmigen Bedruckstoff nach einer zweiten Variante der Erfindung;

Fig. 1

eine schematisierte Vorrichtung zum Herstellen einer strukturierten Oberfläche auf einem bahnförmigen Bedruckstoff nach einer ersten Variante der Erfindung;

Fig. 2

eine schematisierte Vorrichtung zum Herstellen einer strukturierten Oberfläche auf einem bahnförmigen Bedruckstoff nach einer zweiten Variante der Erfindung;

Fig. 5

ein Detail eines Prägewerks der Vorrichtungen der Fig. 1 bis 4.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below. An embodiment of the invention is, without being limited thereto, explained in more detail with reference to the drawing. Showing:

Fig. 3

a schematic device for producing a structured surface on a sheet-shaped substrate according to a first variant of the invention;

Fig. 4

a schematic device for producing a structured surface on a sheet-shaped substrate according to a second variant of the invention;

Fig. 1

a schematic device for producing a structured surface on a web-shaped substrate according to a first variant of the invention;

Fig. 2

a schematic device for producing a structured surface on a web-shaped substrate according to a second variant of the invention;

Fig. 5

a detail of an embossing device of the devices Fig. 1 to 4 ,

The present invention relates to an apparatus for producing a structured surface on a printing substrate. Furthermore, the invention relates to a method for producing a structured surface on a printing substrate.

Moreover, the invention relates to a method for producing a stamping die for use in a device according to the invention and / or a method according to the invention.

Fig. 1 shows a highly schematic of a device 10 according to the invention for producing a structured surface on a web-shaped substrate 11. In the web-shaped substrate 11 is in Fig. 1 one in advance printed substrate, which is held ready on a Rollenzuführeinrichtung 12 in the form of a Bedruckstoffrolle 13.

The device 10 according to the invention comprises a coating unit 14 in order to apply a lacquer layer to the printing material 11. In the coating unit 14 is in the embodiment of Fig. 1 to a working according to the offset printing principle coating unit. It should be noted that other coating plants can be used, which are based on other printing processes, such as coating plants, the high-pressure process, gravure printing or screen printing process or the inkjet process, which also druckformund format variable is - based. The coating unit 14 is used to apply a flat lacquer layer of constant or variable thickness on at least parts of the printing material eleventh

The coating unit 14 is downstream of a stamping 15. The embossing unit 15 serves to transfer a three-dimensional structure into the lacquer layer applied to the printing material 11 with the aid of the coating unit 14 before it is dried. In this case, the embossing unit 14 transfers the three-dimensional structure exclusively into the lacquer layer applied to the printing material 11 with the aid of the coating unit 14 and not into the printing material carrying the lacquer layer, thus accordingly the material structure of the printing material by transferring the three-dimensional structure into the lacquer layer in the area of the embossing unit 15 is not changed.

The embossing unit 15 is followed by a drying or curing device 16 to cure or dry the paint applied with the aid of the coating unit 14 and structured by means of the embossing unit 15 to form the structured surface on the printing substrate 11. The drying or curing device 16 may be an infrared drying device or a UV curing device or an electron beam curing device or a hot air drying device or any other Drying device act by means of which a paint can be cured or dried.

The drying device 16 is downstream of a further processing device 17 to further process the substrate 11 provided with the structured surface. This can be, for example, a folding unit or a cross cutter.

Likewise, the further processing device 17 may be a rewinding device in order subsequently to rewind the printed substrate 11 provided with the structured surface onto a reel.

Fig. 5 shows a detail of the embossing unit 15, which serves to transfer a three-dimensional structure in the applied with the aid of the coating unit 14 on the substrate 11 lacquer layer 18 before drying the lacquer layer. So shows Fig. 5 a printing material 11, which is provided on one side with a flat lacquer layer 18, wherein the embossing unit 15 has a stamping die 19 carrying embossing cylinder 20 and cooperating with the embossing cylinder 20 counter-cylinder 21. The printing material 11 provided with the sheet-like lacquer layer 18 is moved through an embossing gap 22 formed between the embossing cylinder 20 and the counter-cylinder 21, whereby a three-dimensional structure 23 is transferred into the flat lacquer layer 18 of the printing material 11 via the embossing die 19.

As already stated, in the transfer of the three-dimensional structure into the flat lacquer layer 18 with the aid of the embossing die 19, the lacquer layer 18 applied to the printing substrate 11 has not yet hardened. The curing takes place rather downstream of the embossing unit 15 in the drying device 16, which is downstream of the embossing machine 15.

During transport of the printing material 11 provided with the lacquer layer 18 through the between the embossing cylinder 20 and the counter-cylinder 21, the procedure is such that a relatively low pressure is exerted on the printing material 11 in the two-dimensional lacquer layer 18 during the transfer of the three-dimensional structure. This prevents that the not yet cured lacquer layer 18, which still assumes a viscous state, is crushed. On the contrary, the pressure is sufficient to not transfer the three-dimensional structure predetermined by the embossing die 19 into the lacquer layer 18, however, into the printing material 11.

In the illustrated embodiment of the Fig. 5 If the embossing die 19 is a plate that can be tensioned on the embossing cylinder 20 or a cloth that can be tensioned on the embossing cylinder 20, a so-called leading end and a so-called trailing end of such a plate-like or cloth-like embossing die 19 can be tensioned in a chucking channel 24 of the embossing cylinder 20. In contrast, it is also possible to form the embossing patrix 19 as a sleeve-like sleeve, which can then be pushed onto a clamping channel-free embossing cylinder 20 in the axial direction. Furthermore, it is also possible to apply the embossing die on a ferromagnetic sheet and to clamp this on a magnetic or magnetizable embossing cylinder. This embodiment has the advantage that in the case of partial painting or partial stamping of the coating, the at least one stamping die can be positioned as desired on the stamping cylinder.

The embossing die 19 received by the embossing cylinder 20 may be flexible or rigid. Then, when the embossing die 19 is flexible, the counter-cylinder 21 is preferably rigid on its surface. On the other hand, if the embossing patrix 19 is rigid, the counter-cylinder 21 is preferably flexible on its surface so as to allow, in combination on the one hand, a secure transfer of the three-dimensional structure starting from the embossing patrix 19 into the two-layer lacquer layer 18 of the printing substrate 11 and, on the other hand, the small one Pressure in the transfer of the three-dimensional structure in the To ensure lacquer layer 18 and thus to prevent squeezing of the lacquer layer 18 in the embossing unit 15 and damage to the printing material 11.

Preferably, the embossing cylinder 20 received embossing die 19 has an embossing surface of a paint-repellent material. In this case, it can then be prevented that the not yet cured lacquer of the sheet-like lacquer layer 18 in the embossing unit 15 adheres to the embossing die 19 and contaminates the same. This can improve the quality of the structured surface being formed.

If necessary, the embossing machine 15 may comprise a cleaning device, which is preferably associated with the embossing cylinder 20, namely such that the embossing die 19 can be continuously or temporarily cleaned during the embossing process.

With such a cleaning device residues of paint and optionally color, which adhere to the embossing patrix 19 in the formation of the embossing on the lacquer layer 18, are removed from the same. As a result, the quality of the forming structured surface can be permanently ensured.

According to an advantageous embodiment of the invention, the embossing cylinder 20 and the counter cylinder 21 comprehensive cylinder group of the embossing 15 is associated with a direct drive to drive embossing cylinder 20 and counter-cylinder 21 in the embossing machine 13 self-powered via this direct drive. As a result, it is then possible to synchronously drive the cylinder group of the embossing mechanism 15 comprising the embossing cylinder 20 and the countercylinder 21 to the coating unit 14, so that no sluggish or braking slip then arises in the region of the embossing unit 15. As a result, the quality of the structured surface on the printing material 11 can be further increased.

In the embodiment of Fig. 1 the formation of the structured surface on the substrate 11 takes place offline for printing the same. Fig. 2 In contrast, shows an embodiment of the invention, in which the device 10 is integrated to produce a structured surface on a substrate in a web printing press. Thus, the device 10 according to the invention is preceded by a plurality of printing units 25 comprehensive printing unit 26 for printing a web-shaped substrate 11, wherein in Fig. 2 the web-shaped printing substrate 11 is transported in the horizontal direction by the printing units 25. Such a web transport of the printing material web is customary in web presses designed as commercial printing presses. However, the invention is not limited to such a configuration of a web-fed printing machine. On the contrary, the invention can also be used in web-fed printing presses with a vertical web run of the web-shaped printing material web to be printed, as is usual in newspaper printing presses. The printing units 25 may preferably be offset and / or gravure and / or flexo printing units and / or digital printing units.

In Fig. 2 Accordingly, the production of the structured surface on the printed substrate 11 is inline for printing the same.

With regard to the remaining details, the embodiment of the Fig. 2 with the embodiment of Fig. 1 so that to avoid unnecessary repetition for the embodiment of Fig. 2 to the comments on the embodiment of Fig. 1 is referenced. Identical reference numbers have been used for identical assemblies.

As in 3 and 4 The invention can also be used in printing presses designed as sheet-fed printing presses. So shows Fig. 3 an embodiment in which in a device 10 according to the invention, which comprises at least the coating unit 14, the embossing unit 15 and the drying device 16, Printed sheets offline to be printed on the same with a structured surface. Printed sheets are held ready as a stack in a feeder 27 and then stacked on the same in a boom 27 to form the structured surface.

In the variant of Fig. 4 the formation of the structured surface takes place on printed sheet-shaped substrates inline for printing the same, according to Fig. 4 the inventive device 10 printing units 29 are upstream of a sheet-fed press.

As already mentioned, a structured surface can be formed with the method according to the invention, in particular on thin substrates, on sensitive substrates such as corrugated board and foils. In particular, therefore, the invention finds use for forming a structured film on a film-like material. Such a film-like printing material may be, for example, a film of a thermoplastic material or else a film of aluminum.

Drying of the structured surface is preferably carried out using UV drying, since under UV radiation, dryable lacquers can be dried particularly quickly.

The embossing patterns 19 used in the method according to the invention and in the device according to the invention can be produced by transferring to a blank 30 provided a digital print image generated by means of a digital image data generation method by means of an exposure process. Subsequently, the embossing profile 31 is cured and unexposed profile areas are washed out. This makes it possible to produce a stamping die 19 simply and reliably.

Alternatively, it is possible to produce a stamping die 19 by applying the blanking profile 31 to a blank 30 provided by means of a three-dimensional inkjet printing method and thus a three-dimensional inkjet printing technique.

With the invention, it is possible to form a structured surface on at least one surface thereof even with thin substrates and film-like substrates. For this purpose, a lacquer layer is applied to the corresponding surface of the printing material, wherein the not yet dried lacquer layer is provided in a stamping mill with a three-dimensional structure. Subsequently, the drying of the lacquer layer takes place to form the structured surface on the substrate.

The invention can be used in particular to form three-dimensional structures on a surface of a printed product in packaging printing or decor printing or security printing.

In security printing, structured surfaces can be applied to a substrate, which increase the security against counterfeiting.

Claims (18)

Device for producing a structured surface on a printing substrate, having at least the following components: a coating unit (14) for applying a lacquer layer (18) to a printing material (11); an embossing unit (15) downstream of the coating unit (14) for transferring a three-dimensional structure to the lacquer layer (18) applied to the printing material by means of the coating unit (14) before drying or hardening thereof; a drying or hardening device (16) downstream of the embossing unit (15) for drying or hardening the lacquer layer (18) applied with the aid of the coating unit (14) and structured with the aid of the embossing unit (15) to form the structured surface on the printing substrate ( 11). Apparatus according to claim 1, characterized in that the coating unit (15) a flat lacquer layer (18) of constant or variable thickness on at least parts of the printing material (11) applies. Apparatus according to claim 1 or 2, characterized in that the embossing unit (15) does not transfer the three-dimensional structure exclusively into the lacquer layer (18) applied with the aid of the coating unit (14) into the printing material (11) carrying the lacquer layer (18). Device according to one of claims 1 to 3, characterized in that the embossing a embossing die (19) carrying the embossing cylinder (20) and cooperating with the embossing cylinder counter-cylinder (21), wherein provided with the lacquer layer printing material by a between the embossing cylinder and counter cylinder formed embossing gap (22) is movable therethrough. Apparatus according to claim 4, characterized in that the embossing cylinder (20) received embossing die (19) is flexible and a surface of the counter-cylinder (21) is rigid. Apparatus according to claim 4, characterized in that the embossing cylinder (20) received embossing die (19) rigid and a surface of the counter-cylinder (21) is flexible. Device according to one of claims 4 to 6, characterized in that the embossing die (19) received by the embossing cylinder (20) is designed as a plate which can be tensioned on the embossing cylinder (20) or as a cloth which can be tensioned on the embossing cylinder (20). Device according to one of claims 4 to 6, characterized in that the embossing die (19) received by the embossing cylinder (20) is designed as a sleeve positionable on the embossing cylinder (20). Device according to one of claims 4 to 6, characterized in that the embossing die (19) received by the embossing cylinder (20) is designed as an embossing die (19) which can be received on a magnetic or magnetizable embossing cylinder (20) and is applied to a ferromagnetic base body , Device according to one of claims 4 to 9, characterized in that the embossing die (19) received by the embossing cylinder (20) has an embossing surface of a paint-repellent material. Device according to one of claims 4 to 10, characterized in that the cylinder group of embossing cylinder (20) and the counter-cylinder (21) is driven by an engine directly via a direct drive. Device according to one of claims 1 to 11, characterized in that the drying or curing device (16) is a UV dryer. Device according to one of claims 1 to 11, characterized in that the drying or curing device is a device for electron beam curing. Process for producing a structured surface on a printing substrate, comprising at least the following steps: Applying a lacquer layer (18) to a printing material (11); Transferring a three-dimensional structure into the lacquer layer (18) applied to the printing substrate (11) before drying it; Drying of the structured lacquer layer (18) to form the structured surface on the substrate (11). A method according to claim 14, characterized in that the same is carried out on a device according to one of claims 1 to 13. Use of a device according to one of claims 1 to 13 and / or a method according to claim 14 or 15 for producing a structured surface on a film-like printing substrate. Method for producing a stamping die for use in a device according to one of claims 1 to 12 and / or in a method according to claim 14 or 15, comprising at least the following steps: Providing a blank; Generating a digital embossing profile by means of digital image data generation; Transferring the digital embossing profile to the blank by means of an exposure process; Curing of the embossing profile and ejection of unexposed profile areas. Method for producing a stamping die for use in a device according to one of claims 1 to 12 and / or in a method according to claim 14 or 15, comprising at least the following steps: Providing a blank; Applying an embossing profile to the blank by means of three-dimensional inkjet printing technology.

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